Rollup merge of #122749 - aliemjay:region-err, r=compiler-errors

make `type_flags(ReError) & HAS_ERROR`

Self-explanatory. `TypeVisitableExt::references_error(ReError)` incorrectly returned `false`.

Author: jhpratt

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -434,10 +434,6 @@ fn check_opaque_type_parameter_valid(
     // Only check the parent generics, which will ignore any of the
     // duplicated lifetime args that come from reifying late-bounds.
     for (i, arg) in opaque_type_key.args.iter().take(parent_generics.count()).enumerate() {
-        if let Err(guar) = arg.error_reported() {
-            return Err(guar);
-        }
-
         let arg_is_param = match arg.unpack() {
             GenericArgKind::Type(ty) => matches!(ty.kind(), ty::Param(_)),
             GenericArgKind::Lifetime(lt) if is_ty_alias => {

compiler/rustc_infer/src/infer/opaque_types/mod.rs

@@ -94,9 +94,6 @@ impl<'tcx> InferCtxt<'tcx> {
         cause: &ObligationCause<'tcx>,
         param_env: ty::ParamEnv<'tcx>,
     ) -> InferResult<'tcx, ()> {
-        if a.references_error() || b.references_error() {
-            return Ok(InferOk { value: (), obligations: vec![] });
-        }
         let process = |a: Ty<'tcx>, b: Ty<'tcx>| match *a.kind() {
             ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) if def_id.is_local() => {
                 let def_id = def_id.expect_local();

compiler/rustc_middle/src/ty/region.rs

@@ -251,6 +251,7 @@ impl<'tcx> Region<'tcx> {
             }
             ty::ReError(_) => {
                 flags = flags | TypeFlags::HAS_FREE_REGIONS;
+                flags = flags | TypeFlags::HAS_ERROR;
             }
         }
 

compiler/rustc_type_ir/src/flags.rs

@@ -85,7 +85,7 @@ bitflags! {
                                           | TypeFlags::HAS_TY_INHERENT.bits()
                                           | TypeFlags::HAS_CT_PROJECTION.bits();
 
-        /// Is an error type/const reachable?
+        /// Is an error type/lifetime/const reachable?
         const HAS_ERROR                   = 1 << 15;
 
         /// Does this have any region that "appears free" in the type?

tests/ui/async-await/in-trait/return-not-existing-pair.rs

@@ -9,8 +9,7 @@ trait MyTrait<'a, 'b, T> {
 impl<'a, 'b, T, U> MyTrait<T> for U {
     //~^ ERROR: implicit elided lifetime not allowed here [E0726]
     async fn foo(_: T) -> (&'a U, &'b T) {}
-    //~^ ERROR: method `foo` has a `&self` declaration in the trait, but not in the impl [E0186]
-    //~| ERROR: mismatched types [E0308]
+    //~^ ERROR: mismatched types [E0308]
 }
 
 fn main() {}

tests/ui/async-await/in-trait/return-not-existing-pair.stderr

@@ -15,15 +15,6 @@ error[E0412]: cannot find type `ConnImpl` in this scope
 LL |     async fn foo(&'a self, key: &'b T) -> (&'a ConnImpl, &'b T);
    |                                                ^^^^^^^^ not found in this scope
 
-error[E0186]: method `foo` has a `&self` declaration in the trait, but not in the impl
-  --> $DIR/return-not-existing-pair.rs:11:5
-   |
-LL |     async fn foo(&'a self, key: &'b T) -> (&'a ConnImpl, &'b T);
-   |     ------------------------------------------------------------ `&self` used in trait
-...
-LL |     async fn foo(_: T) -> (&'a U, &'b T) {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `&self` in impl
-
 error[E0308]: mismatched types
   --> $DIR/return-not-existing-pair.rs:11:42
    |
@@ -33,7 +24,7 @@ LL |     async fn foo(_: T) -> (&'a U, &'b T) {}
    = note:  expected tuple `(&'a U, &'b T)`
            found unit type `()`
 
-error: aborting due to 4 previous errors
+error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0186, E0308, E0412, E0726.
-For more information about an error, try `rustc --explain E0186`.
+Some errors have detailed explanations: E0308, E0412, E0726.
+For more information about an error, try `rustc --explain E0308`.

tests/ui/async-await/in-trait/unconstrained-impl-region.rs

@@ -14,6 +14,7 @@ impl<'a> Actor for () {
 //~^ ERROR the lifetime parameter `'a` is not constrained by the impl trait, self type, or predicates
     type Message = &'a ();
     async fn on_mount(self, _: impl Inbox<&'a ()>) {}
+    //~^ ERROR the trait bound `impl Inbox<&'a ()>: Inbox<&'a ()>` is not satisfied
 }
 
 fn main() {}

tests/ui/async-await/in-trait/unconstrained-impl-region.stderr

@@ -1,9 +1,26 @@
+error[E0277]: the trait bound `impl Inbox<&'a ()>: Inbox<&'a ()>` is not satisfied
+  --> $DIR/unconstrained-impl-region.rs:16:5
+   |
+LL |     async fn on_mount(self, _: impl Inbox<&'a ()>) {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Inbox<&'a ()>` is not implemented for `impl Inbox<&'a ()>`
+   |
+note: required by a bound in `<() as Actor>::on_mount`
+  --> $DIR/unconstrained-impl-region.rs:16:37
+   |
+LL |     async fn on_mount(self, _: impl Inbox<&'a ()>) {}
+   |                                     ^^^^^^^^^^^^^ required by this bound in `<() as Actor>::on_mount`
+help: consider further restricting this bound
+   |
+LL |     async fn on_mount(self, _: impl Inbox<&'a ()> + Inbox<&'a ()>) {}
+   |                                                   +++++++++++++++
+
 error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait, self type, or predicates
   --> $DIR/unconstrained-impl-region.rs:13:6
    |
 LL | impl<'a> Actor for () {
    |      ^^ unconstrained lifetime parameter
 
-error: aborting due to 1 previous error
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0207`.
+Some errors have detailed explanations: E0207, E0277.
+For more information about an error, try `rustc --explain E0207`.

tests/ui/const-generics/generic_const_exprs/issue-109141.rs

@@ -4,6 +4,7 @@
 impl EntriesBuffer {
     fn a(&self) -> impl Iterator {
         self.0.iter_mut() //~ ERROR: cannot borrow `*self.0` as mutable, as it is behind a `&` reference
+                          //~| ERROR captures lifetime that does not appear in bounds
     }
 }
 

tests/ui/const-generics/generic_const_exprs/issue-109141.stderr

@@ -1,5 +1,5 @@
 error[E0425]: cannot find value `HashesEntryLEN` in this scope
-  --> $DIR/issue-109141.rs:10:32
+  --> $DIR/issue-109141.rs:11:32
    |
 LL | struct EntriesBuffer(Box<[[u8; HashesEntryLEN]; 5]>);
    |                                ^^^^^^^^^^^^^^ not found in this scope
@@ -20,7 +20,22 @@ help: consider changing this to be a mutable reference
 LL |     fn a(&mut self) -> impl Iterator {
    |          ~~~~~~~~~
 
-error: aborting due to 2 previous errors
+error[E0700]: hidden type for `impl Iterator` captures lifetime that does not appear in bounds
+  --> $DIR/issue-109141.rs:6:9
+   |
+LL |     fn a(&self) -> impl Iterator {
+   |          -----     ------------- opaque type defined here
+   |          |
+   |          hidden type `std::slice::IterMut<'_, [u8; {const error}]>` captures the anonymous lifetime defined here
+LL |         self.0.iter_mut()
+   |         ^^^^^^^^^^^^^^^^^
+   |
+help: to declare that `impl Iterator` captures `'_`, you can add an explicit `'_` lifetime bound
+   |
+LL |     fn a(&self) -> impl Iterator + '_ {
+   |                                  ++++
+
+error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0425, E0596.
+Some errors have detailed explanations: E0425, E0596, E0700.
 For more information about an error, try `rustc --explain E0425`.